SSB proteins are essential to the proess of DNA replication. Their role is to stabilize the single-stranded DNA intermediates formed during DNA unwinding. We have solved the structure of the apo form of the DNA-binding domain of SSB from Escherichai coli using MAD phasing methods. More recently, we have collected MAD data on crystals of complexes of the same domain bound to an oligo dC35. This structure has been solved. We now have crystals of the full-length protein/DNA complex obtained using the selenomethionine-derivatized full-lengh SSB. Synchrotron radiation will also be advantageous to increase the resolution of our data.